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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Facebook
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
6
7#include <linux/sched.h>
8#include <linux/random.h>
9#include <linux/sbitmap.h>
10#include <linux/seq_file.h>
11
12static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)
13{
14 unsigned depth = sb->depth;
15
16 sb->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
17 if (!sb->alloc_hint)
18 return -ENOMEM;
19
20 if (depth && !sb->round_robin) {
21 int i;
22
23 for_each_possible_cpu(i)
24 *per_cpu_ptr(sb->alloc_hint, i) = prandom_u32() % depth;
25 }
26 return 0;
27}
28
29static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,
30 unsigned int depth)
31{
32 unsigned hint;
33
34 hint = this_cpu_read(*sb->alloc_hint);
35 if (unlikely(hint >= depth)) {
36 hint = depth ? prandom_u32() % depth : 0;
37 this_cpu_write(*sb->alloc_hint, hint);
38 }
39
40 return hint;
41}
42
43static inline void update_alloc_hint_after_get(struct sbitmap *sb,
44 unsigned int depth,
45 unsigned int hint,
46 unsigned int nr)
47{
48 if (nr == -1) {
49 /* If the map is full, a hint won't do us much good. */
50 this_cpu_write(*sb->alloc_hint, 0);
51 } else if (nr == hint || unlikely(sb->round_robin)) {
52 /* Only update the hint if we used it. */
53 hint = nr + 1;
54 if (hint >= depth - 1)
55 hint = 0;
56 this_cpu_write(*sb->alloc_hint, hint);
57 }
58}
59
60/*
61 * See if we have deferred clears that we can batch move
62 */
63static inline bool sbitmap_deferred_clear(struct sbitmap_word *map)
64{
65 unsigned long mask;
66
67 if (!READ_ONCE(map->cleared))
68 return false;
69
70 /*
71 * First get a stable cleared mask, setting the old mask to 0.
72 */
73 mask = xchg(&map->cleared, 0);
74
75 /*
76 * Now clear the masked bits in our free word
77 */
78 atomic_long_andnot(mask, (atomic_long_t *)&map->word);
79 BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));
80 return true;
81}
82
83int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
84 gfp_t flags, int node, bool round_robin,
85 bool alloc_hint)
86{
87 unsigned int bits_per_word;
88 unsigned int i;
89
90 if (shift < 0)
91 shift = sbitmap_calculate_shift(depth);
92
93 bits_per_word = 1U << shift;
94 if (bits_per_word > BITS_PER_LONG)
95 return -EINVAL;
96
97 sb->shift = shift;
98 sb->depth = depth;
99 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
100 sb->round_robin = round_robin;
101
102 if (depth == 0) {
103 sb->map = NULL;
104 return 0;
105 }
106
107 if (alloc_hint) {
108 if (init_alloc_hint(sb, flags))
109 return -ENOMEM;
110 } else {
111 sb->alloc_hint = NULL;
112 }
113
114 sb->map = kcalloc_node(sb->map_nr, sizeof(*sb->map), flags, node);
115 if (!sb->map) {
116 free_percpu(sb->alloc_hint);
117 return -ENOMEM;
118 }
119
120 for (i = 0; i < sb->map_nr; i++) {
121 sb->map[i].depth = min(depth, bits_per_word);
122 depth -= sb->map[i].depth;
123 }
124 return 0;
125}
126EXPORT_SYMBOL_GPL(sbitmap_init_node);
127
128void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
129{
130 unsigned int bits_per_word = 1U << sb->shift;
131 unsigned int i;
132
133 for (i = 0; i < sb->map_nr; i++)
134 sbitmap_deferred_clear(&sb->map[i]);
135
136 sb->depth = depth;
137 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
138
139 for (i = 0; i < sb->map_nr; i++) {
140 sb->map[i].depth = min(depth, bits_per_word);
141 depth -= sb->map[i].depth;
142 }
143}
144EXPORT_SYMBOL_GPL(sbitmap_resize);
145
146static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
147 unsigned int hint, bool wrap)
148{
149 int nr;
150
151 /* don't wrap if starting from 0 */
152 wrap = wrap && hint;
153
154 while (1) {
155 nr = find_next_zero_bit(word, depth, hint);
156 if (unlikely(nr >= depth)) {
157 /*
158 * We started with an offset, and we didn't reset the
159 * offset to 0 in a failure case, so start from 0 to
160 * exhaust the map.
161 */
162 if (hint && wrap) {
163 hint = 0;
164 continue;
165 }
166 return -1;
167 }
168
169 if (!test_and_set_bit_lock(nr, word))
170 break;
171
172 hint = nr + 1;
173 if (hint >= depth - 1)
174 hint = 0;
175 }
176
177 return nr;
178}
179
180static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
181 unsigned int alloc_hint)
182{
183 struct sbitmap_word *map = &sb->map[index];
184 int nr;
185
186 do {
187 nr = __sbitmap_get_word(&map->word, map->depth, alloc_hint,
188 !sb->round_robin);
189 if (nr != -1)
190 break;
191 if (!sbitmap_deferred_clear(map))
192 break;
193 } while (1);
194
195 return nr;
196}
197
198static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
199{
200 unsigned int i, index;
201 int nr = -1;
202
203 index = SB_NR_TO_INDEX(sb, alloc_hint);
204
205 /*
206 * Unless we're doing round robin tag allocation, just use the
207 * alloc_hint to find the right word index. No point in looping
208 * twice in find_next_zero_bit() for that case.
209 */
210 if (sb->round_robin)
211 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
212 else
213 alloc_hint = 0;
214
215 for (i = 0; i < sb->map_nr; i++) {
216 nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);
217 if (nr != -1) {
218 nr += index << sb->shift;
219 break;
220 }
221
222 /* Jump to next index. */
223 alloc_hint = 0;
224 if (++index >= sb->map_nr)
225 index = 0;
226 }
227
228 return nr;
229}
230
231int sbitmap_get(struct sbitmap *sb)
232{
233 int nr;
234 unsigned int hint, depth;
235
236 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
237 return -1;
238
239 depth = READ_ONCE(sb->depth);
240 hint = update_alloc_hint_before_get(sb, depth);
241 nr = __sbitmap_get(sb, hint);
242 update_alloc_hint_after_get(sb, depth, hint, nr);
243
244 return nr;
245}
246EXPORT_SYMBOL_GPL(sbitmap_get);
247
248static int __sbitmap_get_shallow(struct sbitmap *sb,
249 unsigned int alloc_hint,
250 unsigned long shallow_depth)
251{
252 unsigned int i, index;
253 int nr = -1;
254
255 index = SB_NR_TO_INDEX(sb, alloc_hint);
256
257 for (i = 0; i < sb->map_nr; i++) {
258again:
259 nr = __sbitmap_get_word(&sb->map[index].word,
260 min(sb->map[index].depth, shallow_depth),
261 SB_NR_TO_BIT(sb, alloc_hint), true);
262 if (nr != -1) {
263 nr += index << sb->shift;
264 break;
265 }
266
267 if (sbitmap_deferred_clear(&sb->map[index]))
268 goto again;
269
270 /* Jump to next index. */
271 index++;
272 alloc_hint = index << sb->shift;
273
274 if (index >= sb->map_nr) {
275 index = 0;
276 alloc_hint = 0;
277 }
278 }
279
280 return nr;
281}
282
283int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)
284{
285 int nr;
286 unsigned int hint, depth;
287
288 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
289 return -1;
290
291 depth = READ_ONCE(sb->depth);
292 hint = update_alloc_hint_before_get(sb, depth);
293 nr = __sbitmap_get_shallow(sb, hint, shallow_depth);
294 update_alloc_hint_after_get(sb, depth, hint, nr);
295
296 return nr;
297}
298EXPORT_SYMBOL_GPL(sbitmap_get_shallow);
299
300bool sbitmap_any_bit_set(const struct sbitmap *sb)
301{
302 unsigned int i;
303
304 for (i = 0; i < sb->map_nr; i++) {
305 if (sb->map[i].word & ~sb->map[i].cleared)
306 return true;
307 }
308 return false;
309}
310EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
311
312static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
313{
314 unsigned int i, weight = 0;
315
316 for (i = 0; i < sb->map_nr; i++) {
317 const struct sbitmap_word *word = &sb->map[i];
318
319 if (set)
320 weight += bitmap_weight(&word->word, word->depth);
321 else
322 weight += bitmap_weight(&word->cleared, word->depth);
323 }
324 return weight;
325}
326
327static unsigned int sbitmap_cleared(const struct sbitmap *sb)
328{
329 return __sbitmap_weight(sb, false);
330}
331
332unsigned int sbitmap_weight(const struct sbitmap *sb)
333{
334 return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
335}
336EXPORT_SYMBOL_GPL(sbitmap_weight);
337
338void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
339{
340 seq_printf(m, "depth=%u\n", sb->depth);
341 seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
342 seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
343 seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
344 seq_printf(m, "map_nr=%u\n", sb->map_nr);
345}
346EXPORT_SYMBOL_GPL(sbitmap_show);
347
348static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
349{
350 if ((offset & 0xf) == 0) {
351 if (offset != 0)
352 seq_putc(m, '\n');
353 seq_printf(m, "%08x:", offset);
354 }
355 if ((offset & 0x1) == 0)
356 seq_putc(m, ' ');
357 seq_printf(m, "%02x", byte);
358}
359
360void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
361{
362 u8 byte = 0;
363 unsigned int byte_bits = 0;
364 unsigned int offset = 0;
365 int i;
366
367 for (i = 0; i < sb->map_nr; i++) {
368 unsigned long word = READ_ONCE(sb->map[i].word);
369 unsigned long cleared = READ_ONCE(sb->map[i].cleared);
370 unsigned int word_bits = READ_ONCE(sb->map[i].depth);
371
372 word &= ~cleared;
373
374 while (word_bits > 0) {
375 unsigned int bits = min(8 - byte_bits, word_bits);
376
377 byte |= (word & (BIT(bits) - 1)) << byte_bits;
378 byte_bits += bits;
379 if (byte_bits == 8) {
380 emit_byte(m, offset, byte);
381 byte = 0;
382 byte_bits = 0;
383 offset++;
384 }
385 word >>= bits;
386 word_bits -= bits;
387 }
388 }
389 if (byte_bits) {
390 emit_byte(m, offset, byte);
391 offset++;
392 }
393 if (offset)
394 seq_putc(m, '\n');
395}
396EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
397
398static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
399 unsigned int depth)
400{
401 unsigned int wake_batch;
402 unsigned int shallow_depth;
403
404 /*
405 * For each batch, we wake up one queue. We need to make sure that our
406 * batch size is small enough that the full depth of the bitmap,
407 * potentially limited by a shallow depth, is enough to wake up all of
408 * the queues.
409 *
410 * Each full word of the bitmap has bits_per_word bits, and there might
411 * be a partial word. There are depth / bits_per_word full words and
412 * depth % bits_per_word bits left over. In bitwise arithmetic:
413 *
414 * bits_per_word = 1 << shift
415 * depth / bits_per_word = depth >> shift
416 * depth % bits_per_word = depth & ((1 << shift) - 1)
417 *
418 * Each word can be limited to sbq->min_shallow_depth bits.
419 */
420 shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
421 depth = ((depth >> sbq->sb.shift) * shallow_depth +
422 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
423 wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
424 SBQ_WAKE_BATCH);
425
426 return wake_batch;
427}
428
429int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
430 int shift, bool round_robin, gfp_t flags, int node)
431{
432 int ret;
433 int i;
434
435 ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,
436 round_robin, true);
437 if (ret)
438 return ret;
439
440 sbq->min_shallow_depth = UINT_MAX;
441 sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
442 atomic_set(&sbq->wake_index, 0);
443 atomic_set(&sbq->ws_active, 0);
444
445 sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
446 if (!sbq->ws) {
447 sbitmap_free(&sbq->sb);
448 return -ENOMEM;
449 }
450
451 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
452 init_waitqueue_head(&sbq->ws[i].wait);
453 atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch);
454 }
455
456 return 0;
457}
458EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
459
460static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
461 unsigned int depth)
462{
463 unsigned int wake_batch = sbq_calc_wake_batch(sbq, depth);
464 int i;
465
466 if (sbq->wake_batch != wake_batch) {
467 WRITE_ONCE(sbq->wake_batch, wake_batch);
468 /*
469 * Pairs with the memory barrier in sbitmap_queue_wake_up()
470 * to ensure that the batch size is updated before the wait
471 * counts.
472 */
473 smp_mb();
474 for (i = 0; i < SBQ_WAIT_QUEUES; i++)
475 atomic_set(&sbq->ws[i].wait_cnt, 1);
476 }
477}
478
479void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
480{
481 sbitmap_queue_update_wake_batch(sbq, depth);
482 sbitmap_resize(&sbq->sb, depth);
483}
484EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
485
486int __sbitmap_queue_get(struct sbitmap_queue *sbq)
487{
488 return sbitmap_get(&sbq->sb);
489}
490EXPORT_SYMBOL_GPL(__sbitmap_queue_get);
491
492int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
493 unsigned int shallow_depth)
494{
495 WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
496
497 return sbitmap_get_shallow(&sbq->sb, shallow_depth);
498}
499EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow);
500
501void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
502 unsigned int min_shallow_depth)
503{
504 sbq->min_shallow_depth = min_shallow_depth;
505 sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
506}
507EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
508
509static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq)
510{
511 int i, wake_index;
512
513 if (!atomic_read(&sbq->ws_active))
514 return NULL;
515
516 wake_index = atomic_read(&sbq->wake_index);
517 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
518 struct sbq_wait_state *ws = &sbq->ws[wake_index];
519
520 if (waitqueue_active(&ws->wait)) {
521 if (wake_index != atomic_read(&sbq->wake_index))
522 atomic_set(&sbq->wake_index, wake_index);
523 return ws;
524 }
525
526 wake_index = sbq_index_inc(wake_index);
527 }
528
529 return NULL;
530}
531
532static bool __sbq_wake_up(struct sbitmap_queue *sbq)
533{
534 struct sbq_wait_state *ws;
535 unsigned int wake_batch;
536 int wait_cnt;
537
538 ws = sbq_wake_ptr(sbq);
539 if (!ws)
540 return false;
541
542 wait_cnt = atomic_dec_return(&ws->wait_cnt);
543 if (wait_cnt <= 0) {
544 int ret;
545
546 wake_batch = READ_ONCE(sbq->wake_batch);
547
548 /*
549 * Pairs with the memory barrier in sbitmap_queue_resize() to
550 * ensure that we see the batch size update before the wait
551 * count is reset.
552 */
553 smp_mb__before_atomic();
554
555 /*
556 * For concurrent callers of this, the one that failed the
557 * atomic_cmpxhcg() race should call this function again
558 * to wakeup a new batch on a different 'ws'.
559 */
560 ret = atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wake_batch);
561 if (ret == wait_cnt) {
562 sbq_index_atomic_inc(&sbq->wake_index);
563 wake_up_nr(&ws->wait, wake_batch);
564 return false;
565 }
566
567 return true;
568 }
569
570 return false;
571}
572
573void sbitmap_queue_wake_up(struct sbitmap_queue *sbq)
574{
575 while (__sbq_wake_up(sbq))
576 ;
577}
578EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
579
580void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
581 unsigned int cpu)
582{
583 /*
584 * Once the clear bit is set, the bit may be allocated out.
585 *
586 * Orders READ/WRITE on the associated instance(such as request
587 * of blk_mq) by this bit for avoiding race with re-allocation,
588 * and its pair is the memory barrier implied in __sbitmap_get_word.
589 *
590 * One invariant is that the clear bit has to be zero when the bit
591 * is in use.
592 */
593 smp_mb__before_atomic();
594 sbitmap_deferred_clear_bit(&sbq->sb, nr);
595
596 /*
597 * Pairs with the memory barrier in set_current_state() to ensure the
598 * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
599 * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
600 * waiter. See the comment on waitqueue_active().
601 */
602 smp_mb__after_atomic();
603 sbitmap_queue_wake_up(sbq);
604
605 if (likely(!sbq->sb.round_robin && nr < sbq->sb.depth))
606 *per_cpu_ptr(sbq->sb.alloc_hint, cpu) = nr;
607}
608EXPORT_SYMBOL_GPL(sbitmap_queue_clear);
609
610void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
611{
612 int i, wake_index;
613
614 /*
615 * Pairs with the memory barrier in set_current_state() like in
616 * sbitmap_queue_wake_up().
617 */
618 smp_mb();
619 wake_index = atomic_read(&sbq->wake_index);
620 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
621 struct sbq_wait_state *ws = &sbq->ws[wake_index];
622
623 if (waitqueue_active(&ws->wait))
624 wake_up(&ws->wait);
625
626 wake_index = sbq_index_inc(wake_index);
627 }
628}
629EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);
630
631void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
632{
633 bool first;
634 int i;
635
636 sbitmap_show(&sbq->sb, m);
637
638 seq_puts(m, "alloc_hint={");
639 first = true;
640 for_each_possible_cpu(i) {
641 if (!first)
642 seq_puts(m, ", ");
643 first = false;
644 seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));
645 }
646 seq_puts(m, "}\n");
647
648 seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
649 seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
650 seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
651
652 seq_puts(m, "ws={\n");
653 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
654 struct sbq_wait_state *ws = &sbq->ws[i];
655
656 seq_printf(m, "\t{.wait_cnt=%d, .wait=%s},\n",
657 atomic_read(&ws->wait_cnt),
658 waitqueue_active(&ws->wait) ? "active" : "inactive");
659 }
660 seq_puts(m, "}\n");
661
662 seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);
663 seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
664}
665EXPORT_SYMBOL_GPL(sbitmap_queue_show);
666
667void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
668 struct sbq_wait_state *ws,
669 struct sbq_wait *sbq_wait)
670{
671 if (!sbq_wait->sbq) {
672 sbq_wait->sbq = sbq;
673 atomic_inc(&sbq->ws_active);
674 add_wait_queue(&ws->wait, &sbq_wait->wait);
675 }
676}
677EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
678
679void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
680{
681 list_del_init(&sbq_wait->wait.entry);
682 if (sbq_wait->sbq) {
683 atomic_dec(&sbq_wait->sbq->ws_active);
684 sbq_wait->sbq = NULL;
685 }
686}
687EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
688
689void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
690 struct sbq_wait_state *ws,
691 struct sbq_wait *sbq_wait, int state)
692{
693 if (!sbq_wait->sbq) {
694 atomic_inc(&sbq->ws_active);
695 sbq_wait->sbq = sbq;
696 }
697 prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
698}
699EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
700
701void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
702 struct sbq_wait *sbq_wait)
703{
704 finish_wait(&ws->wait, &sbq_wait->wait);
705 if (sbq_wait->sbq) {
706 atomic_dec(&sbq->ws_active);
707 sbq_wait->sbq = NULL;
708 }
709}
710EXPORT_SYMBOL_GPL(sbitmap_finish_wait);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Facebook
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
6
7#include <linux/sched.h>
8#include <linux/random.h>
9#include <linux/sbitmap.h>
10#include <linux/seq_file.h>
11
12static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)
13{
14 unsigned depth = sb->depth;
15
16 sb->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
17 if (!sb->alloc_hint)
18 return -ENOMEM;
19
20 if (depth && !sb->round_robin) {
21 int i;
22
23 for_each_possible_cpu(i)
24 *per_cpu_ptr(sb->alloc_hint, i) = get_random_u32_below(depth);
25 }
26 return 0;
27}
28
29static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,
30 unsigned int depth)
31{
32 unsigned hint;
33
34 hint = this_cpu_read(*sb->alloc_hint);
35 if (unlikely(hint >= depth)) {
36 hint = depth ? get_random_u32_below(depth) : 0;
37 this_cpu_write(*sb->alloc_hint, hint);
38 }
39
40 return hint;
41}
42
43static inline void update_alloc_hint_after_get(struct sbitmap *sb,
44 unsigned int depth,
45 unsigned int hint,
46 unsigned int nr)
47{
48 if (nr == -1) {
49 /* If the map is full, a hint won't do us much good. */
50 this_cpu_write(*sb->alloc_hint, 0);
51 } else if (nr == hint || unlikely(sb->round_robin)) {
52 /* Only update the hint if we used it. */
53 hint = nr + 1;
54 if (hint >= depth - 1)
55 hint = 0;
56 this_cpu_write(*sb->alloc_hint, hint);
57 }
58}
59
60/*
61 * See if we have deferred clears that we can batch move
62 */
63static inline bool sbitmap_deferred_clear(struct sbitmap_word *map,
64 unsigned int depth, unsigned int alloc_hint, bool wrap)
65{
66 unsigned long mask, word_mask;
67
68 guard(raw_spinlock_irqsave)(&map->swap_lock);
69
70 if (!map->cleared) {
71 if (depth == 0)
72 return false;
73
74 word_mask = (~0UL) >> (BITS_PER_LONG - depth);
75 /*
76 * The current behavior is to always retry after moving
77 * ->cleared to word, and we change it to retry in case
78 * of any free bits. To avoid an infinite loop, we need
79 * to take wrap & alloc_hint into account, otherwise a
80 * soft lockup may occur.
81 */
82 if (!wrap && alloc_hint)
83 word_mask &= ~((1UL << alloc_hint) - 1);
84
85 return (READ_ONCE(map->word) & word_mask) != word_mask;
86 }
87
88 /*
89 * First get a stable cleared mask, setting the old mask to 0.
90 */
91 mask = xchg(&map->cleared, 0);
92
93 /*
94 * Now clear the masked bits in our free word
95 */
96 atomic_long_andnot(mask, (atomic_long_t *)&map->word);
97 BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));
98 return true;
99}
100
101int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
102 gfp_t flags, int node, bool round_robin,
103 bool alloc_hint)
104{
105 unsigned int bits_per_word;
106 int i;
107
108 if (shift < 0)
109 shift = sbitmap_calculate_shift(depth);
110
111 bits_per_word = 1U << shift;
112 if (bits_per_word > BITS_PER_LONG)
113 return -EINVAL;
114
115 sb->shift = shift;
116 sb->depth = depth;
117 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
118 sb->round_robin = round_robin;
119
120 if (depth == 0) {
121 sb->map = NULL;
122 return 0;
123 }
124
125 if (alloc_hint) {
126 if (init_alloc_hint(sb, flags))
127 return -ENOMEM;
128 } else {
129 sb->alloc_hint = NULL;
130 }
131
132 sb->map = kvzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);
133 if (!sb->map) {
134 free_percpu(sb->alloc_hint);
135 return -ENOMEM;
136 }
137
138 for (i = 0; i < sb->map_nr; i++)
139 raw_spin_lock_init(&sb->map[i].swap_lock);
140
141 return 0;
142}
143EXPORT_SYMBOL_GPL(sbitmap_init_node);
144
145void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
146{
147 unsigned int bits_per_word = 1U << sb->shift;
148 unsigned int i;
149
150 for (i = 0; i < sb->map_nr; i++)
151 sbitmap_deferred_clear(&sb->map[i], 0, 0, 0);
152
153 sb->depth = depth;
154 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
155}
156EXPORT_SYMBOL_GPL(sbitmap_resize);
157
158static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
159 unsigned int hint, bool wrap)
160{
161 int nr;
162
163 /* don't wrap if starting from 0 */
164 wrap = wrap && hint;
165
166 while (1) {
167 nr = find_next_zero_bit(word, depth, hint);
168 if (unlikely(nr >= depth)) {
169 /*
170 * We started with an offset, and we didn't reset the
171 * offset to 0 in a failure case, so start from 0 to
172 * exhaust the map.
173 */
174 if (hint && wrap) {
175 hint = 0;
176 continue;
177 }
178 return -1;
179 }
180
181 if (!test_and_set_bit_lock(nr, word))
182 break;
183
184 hint = nr + 1;
185 if (hint >= depth - 1)
186 hint = 0;
187 }
188
189 return nr;
190}
191
192static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
193 unsigned int depth,
194 unsigned int alloc_hint,
195 bool wrap)
196{
197 int nr;
198
199 do {
200 nr = __sbitmap_get_word(&map->word, depth,
201 alloc_hint, wrap);
202 if (nr != -1)
203 break;
204 if (!sbitmap_deferred_clear(map, depth, alloc_hint, wrap))
205 break;
206 } while (1);
207
208 return nr;
209}
210
211static int sbitmap_find_bit(struct sbitmap *sb,
212 unsigned int depth,
213 unsigned int index,
214 unsigned int alloc_hint,
215 bool wrap)
216{
217 unsigned int i;
218 int nr = -1;
219
220 for (i = 0; i < sb->map_nr; i++) {
221 nr = sbitmap_find_bit_in_word(&sb->map[index],
222 min_t(unsigned int,
223 __map_depth(sb, index),
224 depth),
225 alloc_hint, wrap);
226
227 if (nr != -1) {
228 nr += index << sb->shift;
229 break;
230 }
231
232 /* Jump to next index. */
233 alloc_hint = 0;
234 if (++index >= sb->map_nr)
235 index = 0;
236 }
237
238 return nr;
239}
240
241static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
242{
243 unsigned int index;
244
245 index = SB_NR_TO_INDEX(sb, alloc_hint);
246
247 /*
248 * Unless we're doing round robin tag allocation, just use the
249 * alloc_hint to find the right word index. No point in looping
250 * twice in find_next_zero_bit() for that case.
251 */
252 if (sb->round_robin)
253 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
254 else
255 alloc_hint = 0;
256
257 return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint,
258 !sb->round_robin);
259}
260
261int sbitmap_get(struct sbitmap *sb)
262{
263 int nr;
264 unsigned int hint, depth;
265
266 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
267 return -1;
268
269 depth = READ_ONCE(sb->depth);
270 hint = update_alloc_hint_before_get(sb, depth);
271 nr = __sbitmap_get(sb, hint);
272 update_alloc_hint_after_get(sb, depth, hint, nr);
273
274 return nr;
275}
276EXPORT_SYMBOL_GPL(sbitmap_get);
277
278static int __sbitmap_get_shallow(struct sbitmap *sb,
279 unsigned int alloc_hint,
280 unsigned long shallow_depth)
281{
282 unsigned int index;
283
284 index = SB_NR_TO_INDEX(sb, alloc_hint);
285 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
286
287 return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);
288}
289
290int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)
291{
292 int nr;
293 unsigned int hint, depth;
294
295 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
296 return -1;
297
298 depth = READ_ONCE(sb->depth);
299 hint = update_alloc_hint_before_get(sb, depth);
300 nr = __sbitmap_get_shallow(sb, hint, shallow_depth);
301 update_alloc_hint_after_get(sb, depth, hint, nr);
302
303 return nr;
304}
305EXPORT_SYMBOL_GPL(sbitmap_get_shallow);
306
307bool sbitmap_any_bit_set(const struct sbitmap *sb)
308{
309 unsigned int i;
310
311 for (i = 0; i < sb->map_nr; i++) {
312 if (sb->map[i].word & ~sb->map[i].cleared)
313 return true;
314 }
315 return false;
316}
317EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
318
319static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
320{
321 unsigned int i, weight = 0;
322
323 for (i = 0; i < sb->map_nr; i++) {
324 const struct sbitmap_word *word = &sb->map[i];
325 unsigned int word_depth = __map_depth(sb, i);
326
327 if (set)
328 weight += bitmap_weight(&word->word, word_depth);
329 else
330 weight += bitmap_weight(&word->cleared, word_depth);
331 }
332 return weight;
333}
334
335static unsigned int sbitmap_cleared(const struct sbitmap *sb)
336{
337 return __sbitmap_weight(sb, false);
338}
339
340unsigned int sbitmap_weight(const struct sbitmap *sb)
341{
342 return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
343}
344EXPORT_SYMBOL_GPL(sbitmap_weight);
345
346void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
347{
348 seq_printf(m, "depth=%u\n", sb->depth);
349 seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
350 seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
351 seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
352 seq_printf(m, "map_nr=%u\n", sb->map_nr);
353}
354EXPORT_SYMBOL_GPL(sbitmap_show);
355
356static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
357{
358 if ((offset & 0xf) == 0) {
359 if (offset != 0)
360 seq_putc(m, '\n');
361 seq_printf(m, "%08x:", offset);
362 }
363 if ((offset & 0x1) == 0)
364 seq_putc(m, ' ');
365 seq_printf(m, "%02x", byte);
366}
367
368void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
369{
370 u8 byte = 0;
371 unsigned int byte_bits = 0;
372 unsigned int offset = 0;
373 int i;
374
375 for (i = 0; i < sb->map_nr; i++) {
376 unsigned long word = READ_ONCE(sb->map[i].word);
377 unsigned long cleared = READ_ONCE(sb->map[i].cleared);
378 unsigned int word_bits = __map_depth(sb, i);
379
380 word &= ~cleared;
381
382 while (word_bits > 0) {
383 unsigned int bits = min(8 - byte_bits, word_bits);
384
385 byte |= (word & (BIT(bits) - 1)) << byte_bits;
386 byte_bits += bits;
387 if (byte_bits == 8) {
388 emit_byte(m, offset, byte);
389 byte = 0;
390 byte_bits = 0;
391 offset++;
392 }
393 word >>= bits;
394 word_bits -= bits;
395 }
396 }
397 if (byte_bits) {
398 emit_byte(m, offset, byte);
399 offset++;
400 }
401 if (offset)
402 seq_putc(m, '\n');
403}
404EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
405
406static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
407 unsigned int depth)
408{
409 unsigned int wake_batch;
410 unsigned int shallow_depth;
411
412 /*
413 * Each full word of the bitmap has bits_per_word bits, and there might
414 * be a partial word. There are depth / bits_per_word full words and
415 * depth % bits_per_word bits left over. In bitwise arithmetic:
416 *
417 * bits_per_word = 1 << shift
418 * depth / bits_per_word = depth >> shift
419 * depth % bits_per_word = depth & ((1 << shift) - 1)
420 *
421 * Each word can be limited to sbq->min_shallow_depth bits.
422 */
423 shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
424 depth = ((depth >> sbq->sb.shift) * shallow_depth +
425 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
426 wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
427 SBQ_WAKE_BATCH);
428
429 return wake_batch;
430}
431
432int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
433 int shift, bool round_robin, gfp_t flags, int node)
434{
435 int ret;
436 int i;
437
438 ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,
439 round_robin, true);
440 if (ret)
441 return ret;
442
443 sbq->min_shallow_depth = UINT_MAX;
444 sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
445 atomic_set(&sbq->wake_index, 0);
446 atomic_set(&sbq->ws_active, 0);
447 atomic_set(&sbq->completion_cnt, 0);
448 atomic_set(&sbq->wakeup_cnt, 0);
449
450 sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
451 if (!sbq->ws) {
452 sbitmap_free(&sbq->sb);
453 return -ENOMEM;
454 }
455
456 for (i = 0; i < SBQ_WAIT_QUEUES; i++)
457 init_waitqueue_head(&sbq->ws[i].wait);
458
459 return 0;
460}
461EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
462
463static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
464 unsigned int depth)
465{
466 unsigned int wake_batch;
467
468 wake_batch = sbq_calc_wake_batch(sbq, depth);
469 if (sbq->wake_batch != wake_batch)
470 WRITE_ONCE(sbq->wake_batch, wake_batch);
471}
472
473void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
474 unsigned int users)
475{
476 unsigned int wake_batch;
477 unsigned int depth = (sbq->sb.depth + users - 1) / users;
478
479 wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES,
480 1, SBQ_WAKE_BATCH);
481
482 WRITE_ONCE(sbq->wake_batch, wake_batch);
483}
484EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);
485
486void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
487{
488 sbitmap_queue_update_wake_batch(sbq, depth);
489 sbitmap_resize(&sbq->sb, depth);
490}
491EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
492
493int __sbitmap_queue_get(struct sbitmap_queue *sbq)
494{
495 return sbitmap_get(&sbq->sb);
496}
497EXPORT_SYMBOL_GPL(__sbitmap_queue_get);
498
499unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
500 unsigned int *offset)
501{
502 struct sbitmap *sb = &sbq->sb;
503 unsigned int hint, depth;
504 unsigned long index, nr;
505 int i;
506
507 if (unlikely(sb->round_robin))
508 return 0;
509
510 depth = READ_ONCE(sb->depth);
511 hint = update_alloc_hint_before_get(sb, depth);
512
513 index = SB_NR_TO_INDEX(sb, hint);
514
515 for (i = 0; i < sb->map_nr; i++) {
516 struct sbitmap_word *map = &sb->map[index];
517 unsigned long get_mask;
518 unsigned int map_depth = __map_depth(sb, index);
519 unsigned long val;
520
521 sbitmap_deferred_clear(map, 0, 0, 0);
522 val = READ_ONCE(map->word);
523 if (val == (1UL << (map_depth - 1)) - 1)
524 goto next;
525
526 nr = find_first_zero_bit(&val, map_depth);
527 if (nr + nr_tags <= map_depth) {
528 atomic_long_t *ptr = (atomic_long_t *) &map->word;
529
530 get_mask = ((1UL << nr_tags) - 1) << nr;
531 while (!atomic_long_try_cmpxchg(ptr, &val,
532 get_mask | val))
533 ;
534 get_mask = (get_mask & ~val) >> nr;
535 if (get_mask) {
536 *offset = nr + (index << sb->shift);
537 update_alloc_hint_after_get(sb, depth, hint,
538 *offset + nr_tags - 1);
539 return get_mask;
540 }
541 }
542next:
543 /* Jump to next index. */
544 if (++index >= sb->map_nr)
545 index = 0;
546 }
547
548 return 0;
549}
550
551int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
552 unsigned int shallow_depth)
553{
554 WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
555
556 return sbitmap_get_shallow(&sbq->sb, shallow_depth);
557}
558EXPORT_SYMBOL_GPL(sbitmap_queue_get_shallow);
559
560void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
561 unsigned int min_shallow_depth)
562{
563 sbq->min_shallow_depth = min_shallow_depth;
564 sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
565}
566EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
567
568static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
569{
570 int i, wake_index, woken;
571
572 if (!atomic_read(&sbq->ws_active))
573 return;
574
575 wake_index = atomic_read(&sbq->wake_index);
576 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
577 struct sbq_wait_state *ws = &sbq->ws[wake_index];
578
579 /*
580 * Advance the index before checking the current queue.
581 * It improves fairness, by ensuring the queue doesn't
582 * need to be fully emptied before trying to wake up
583 * from the next one.
584 */
585 wake_index = sbq_index_inc(wake_index);
586
587 if (waitqueue_active(&ws->wait)) {
588 woken = wake_up_nr(&ws->wait, nr);
589 if (woken == nr)
590 break;
591 nr -= woken;
592 }
593 }
594
595 if (wake_index != atomic_read(&sbq->wake_index))
596 atomic_set(&sbq->wake_index, wake_index);
597}
598
599void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
600{
601 unsigned int wake_batch = READ_ONCE(sbq->wake_batch);
602 unsigned int wakeups;
603
604 if (!atomic_read(&sbq->ws_active))
605 return;
606
607 atomic_add(nr, &sbq->completion_cnt);
608 wakeups = atomic_read(&sbq->wakeup_cnt);
609
610 do {
611 if (atomic_read(&sbq->completion_cnt) - wakeups < wake_batch)
612 return;
613 } while (!atomic_try_cmpxchg(&sbq->wakeup_cnt,
614 &wakeups, wakeups + wake_batch));
615
616 __sbitmap_queue_wake_up(sbq, wake_batch);
617}
618EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
619
620static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag)
621{
622 if (likely(!sb->round_robin && tag < sb->depth))
623 data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);
624}
625
626void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
627 int *tags, int nr_tags)
628{
629 struct sbitmap *sb = &sbq->sb;
630 unsigned long *addr = NULL;
631 unsigned long mask = 0;
632 int i;
633
634 smp_mb__before_atomic();
635 for (i = 0; i < nr_tags; i++) {
636 const int tag = tags[i] - offset;
637 unsigned long *this_addr;
638
639 /* since we're clearing a batch, skip the deferred map */
640 this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;
641 if (!addr) {
642 addr = this_addr;
643 } else if (addr != this_addr) {
644 atomic_long_andnot(mask, (atomic_long_t *) addr);
645 mask = 0;
646 addr = this_addr;
647 }
648 mask |= (1UL << SB_NR_TO_BIT(sb, tag));
649 }
650
651 if (mask)
652 atomic_long_andnot(mask, (atomic_long_t *) addr);
653
654 smp_mb__after_atomic();
655 sbitmap_queue_wake_up(sbq, nr_tags);
656 sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(),
657 tags[nr_tags - 1] - offset);
658}
659
660void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
661 unsigned int cpu)
662{
663 /*
664 * Once the clear bit is set, the bit may be allocated out.
665 *
666 * Orders READ/WRITE on the associated instance(such as request
667 * of blk_mq) by this bit for avoiding race with re-allocation,
668 * and its pair is the memory barrier implied in __sbitmap_get_word.
669 *
670 * One invariant is that the clear bit has to be zero when the bit
671 * is in use.
672 */
673 smp_mb__before_atomic();
674 sbitmap_deferred_clear_bit(&sbq->sb, nr);
675
676 /*
677 * Pairs with the memory barrier in set_current_state() to ensure the
678 * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
679 * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
680 * waiter. See the comment on waitqueue_active().
681 */
682 smp_mb__after_atomic();
683 sbitmap_queue_wake_up(sbq, 1);
684 sbitmap_update_cpu_hint(&sbq->sb, cpu, nr);
685}
686EXPORT_SYMBOL_GPL(sbitmap_queue_clear);
687
688void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
689{
690 int i, wake_index;
691
692 /*
693 * Pairs with the memory barrier in set_current_state() like in
694 * sbitmap_queue_wake_up().
695 */
696 smp_mb();
697 wake_index = atomic_read(&sbq->wake_index);
698 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
699 struct sbq_wait_state *ws = &sbq->ws[wake_index];
700
701 if (waitqueue_active(&ws->wait))
702 wake_up(&ws->wait);
703
704 wake_index = sbq_index_inc(wake_index);
705 }
706}
707EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);
708
709void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
710{
711 bool first;
712 int i;
713
714 sbitmap_show(&sbq->sb, m);
715
716 seq_puts(m, "alloc_hint={");
717 first = true;
718 for_each_possible_cpu(i) {
719 if (!first)
720 seq_puts(m, ", ");
721 first = false;
722 seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));
723 }
724 seq_puts(m, "}\n");
725
726 seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
727 seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
728 seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
729
730 seq_puts(m, "ws={\n");
731 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
732 struct sbq_wait_state *ws = &sbq->ws[i];
733 seq_printf(m, "\t{.wait=%s},\n",
734 waitqueue_active(&ws->wait) ? "active" : "inactive");
735 }
736 seq_puts(m, "}\n");
737
738 seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);
739 seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
740}
741EXPORT_SYMBOL_GPL(sbitmap_queue_show);
742
743void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
744 struct sbq_wait_state *ws,
745 struct sbq_wait *sbq_wait)
746{
747 if (!sbq_wait->sbq) {
748 sbq_wait->sbq = sbq;
749 atomic_inc(&sbq->ws_active);
750 add_wait_queue(&ws->wait, &sbq_wait->wait);
751 }
752}
753EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
754
755void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
756{
757 list_del_init(&sbq_wait->wait.entry);
758 if (sbq_wait->sbq) {
759 atomic_dec(&sbq_wait->sbq->ws_active);
760 sbq_wait->sbq = NULL;
761 }
762}
763EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
764
765void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
766 struct sbq_wait_state *ws,
767 struct sbq_wait *sbq_wait, int state)
768{
769 if (!sbq_wait->sbq) {
770 atomic_inc(&sbq->ws_active);
771 sbq_wait->sbq = sbq;
772 }
773 prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
774}
775EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
776
777void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
778 struct sbq_wait *sbq_wait)
779{
780 finish_wait(&ws->wait, &sbq_wait->wait);
781 if (sbq_wait->sbq) {
782 atomic_dec(&sbq->ws_active);
783 sbq_wait->sbq = NULL;
784 }
785}
786EXPORT_SYMBOL_GPL(sbitmap_finish_wait);